1. Field of the Invention
This invention relates to a document of value, such as a check or ID card or the like, having information specific to the document, in particular user-related data, and to a method for testing the authenticity of the document of value.
2. Related Art
In view of modern reproduction techniques, in particular the rising quality of color copiers, it is becoming ever easier to reproduce documents of value with relatively little effort. This increases the danger of forgeries.
In order to counteract this development one has proposed protecting papers of value by a special coding (DE 24 58 705 A1). Individual parameters of the document, such as characteristic color or print properties, are measured and deposited on the document in coded form. If the coding is to be invisible to the eye one can use luminescent printing inks which are transparent in the visible spectral region. When checking the authenticity of the document one measures the characteristic parameters and compares them with the measuring data stored on the document in coded form.
This procedure offers good protection from forgery as long as the documents of value are coded centrally in protected surroundings and luminescent substances are used which are virtually unavailable commercially.
In the case of check forms having user-related information, such as the account number, it is frequently also useful to include these data in the coding in order to ensure that these data have not been manipulated (i.e., altered). However, checks are usually personalized in decentralized fashion, i.e. the blank forms are produced centrally and then passed on to the issuing bank which applies the user-related data. To permit the method known from DE 24 58 705 A1 to be applied to the user-related data of the check, each bank would therefore have to be equipped with the corresponding devices for applying the coding and in particular the corresponding luminescent substances. This would sacrifice part of the forgery-proof effect since it would make the equipment required for coding much more easily accessible and thus increase the danger of misuse.
The invention is therefore based on the problem of proposing a document of value which avoids the disadvantages of the prior art.